Extension services and Syngenta agronomists are recommending that growers sample soil for soybean cyst nematode (SCN) this fall, after harvest but before a hard freeze or significant snowfall occurs. SCN presence has been expanding across the U.S. every year, yet many growers are still unaware of SCN presence on their farm. Per the South Dakota State University Extension, SCN management starts with testing soil for the nematode, and fall is the best time to do so.
SCN is the most damaging pest to U.S. soybeans. Studies have shown that SCN can contribute to yield losses of 30% to 40% with no visual symptoms above ground. But since the most common SCN yield reduction is less than 15 percent, few obvious above-ground symptomology is most common. “Because this pest is so stealthy, it steals yield across tens of millions of U.S. soybean acres every year, leaving behind few above ground visual traces of its existence,” says Dale Ireland, Ph.D., Seedcare technical product lead at Syngenta.
Not only will sampling in the fall provide timely results in preparation for next season, but it will deliver a more comprehensive image of SCN populations. Because SCN has multiple generations throughout one season, testing mid-season will not provide a complete picture of the severity of a grower’s SCN problem.
Despite SCN presence expanding across the U.S. every year, awareness of the severe threat SCN poses is low. According to a Syngenta survey of more than 1,000 U.S. soybean growers from 17 states, 64% of the growers know little about SCN scouting and sampling. This low awareness poses a problem because SCN is most manageable when populations are still small. If SCN goes untreated, nematode numbers can grow rapidly. It is easier to keep low SCN population densities low than it is to manage high SCN numbers, according to the Iowa State University Extension.
While SCN-resistant soybean varieties have been a common tool for control, decreasing efficacy of the most common source of genetic resistance, PI88788, makes it critical to incorporate a broader management program. In addition to planting resistant varieties, growers are encouraged to practice crop rotation and plant varieties treated with a seed-applied nematicide. Once SCN is present, it cannot ever be entirely eliminated. To properly manage SCN, growers must use all the tools available.
“The time is now to fight back against SCN,” said Palle Pedersen, Ph.D., head of Seedcare product marketing for Syngenta. “We are standing at the edge of a cliff and can fall fast if we don’t start dealing with this challenge.”
To help explain the severe threat SCN poses, Syngenta teamed up with university experts across the Midwest to create a series of videos. Available on ClarivaCompleteBeans.com, these videos explore the challenges and provide in-depth management recommendations.
“When I talk to farmers, I don’t tell them to go sample to see if they have it. They should assume they already have it because it’s so widespread,” emphasizes Jason Bond, plant pathologist at Southern Illinois University and one of the featured experts in the videos. “Sampling is good to see what my population numbers are, and then what my management strategies are doing to try to reduce those populations.”
If soil samples test positive for SCN, it’s not too late. In addition to planting an SCN-resistant variety and practicing crop rotation, many universities now recommend incorporating a seed-applied nematicide like Clariva® Complete Beans seed treatment, a combination of separately registered products, to help manage SCN populations – including those becoming resistant to SCN-resistant genetics. Clariva Complete Beans delivers lethal, season-long protection against SCN and enhances the performance of SCN-resistant varieties.
To learn more about the spread of SCN and how to best protect soybeans, visit the Tools to Grow More Soybeans resource page.